Fiber optic technology has been recognized for its high bandwidth capacity over longer distances, enhanced overall network reliability and service quality. Fiber to the premises (“FTTP”), as opposed to fiber to the node (“FTTN”) or fiber to the curb (“FTTC”) delivery, enables service providers to deliver substantial bandwidth and a wide range of applications directly to business and residential subscribers. For example, FTTP can accommodate the so-called “triple-play” bundle of services, e.g., high-speed Internet access and networking, multiple telephone lines and high-definition and interactive video applications.
Utilizing FTTP, however, involves equipping each subscriber premises with the ability to receive an optical signal and convert it into a signal compatible with pre-existing wiring in the premises (e.g., twisted pair and coaxial). For bi-directional communication with the network, the premises should be equipped with the ability to convert outbound signals into optical signals. In some cases, these abilities are implemented with a passive optical network (“PON”), with each premises having a dedicated optical network unit (“ONU”) for transceiving optical and electrical signals. In some instances, the ONU for a given subscriber is mounted outdoors.
Generally speaking, a PON is a point-to-multipoint fiber to the premises network architecture in which unpowered optical splitters are used to enable a single optical fiber to serve multiple (e.g., 32) premises. A PON can include an optical line termination (“OLT”) at the service provider's central office and a PON module for each end user. Some currently implemented PONs employ the ITU-T G.983 standard, sometimes called “BPON” or “broadband PON.” BPON includes support for wavelength division multiplexing, dynamic and higher upstream bandwidth allocation, and survivability. It also includes a standard management interface, called OMCI, between the OLT and PON module, enabling mixed-vendor networks. BPON supports bit rates of about 622 Mbits/second downstream and about 155 Mbits/second upstream. The next generation standard is ITU-T G.984, sometimes called “GPON” or “gigabit PON.” Compared to BPON, GPON supports higher rates (2,488 Mbits/second downstream and 1,244 Mbits/second upstream), enhanced security, and choice of Layer 2 protocol (e.g., ATM, GEM, Ethernet).
Certain electro-optical transceiving functions are performed by a PON module (or “transceiver module”) that is disposed inside the ONU. The PON module will vary with the type of PON with which it is associated (e.g., BPON module, GPON module, etc.). In some cases, the module includes a bulk optic WDM module that separates the wavelengths of the incoming optical signal. Each of the wavelengths is then manipulated accordingly. The continuous downstream data (e.g., 1490 nm) is filtered and amplified by a limiter amplifier IC. The burst upstream data originating from the premises is converted to an optical signal (e.g., at 1310 nm) and is controlled by a burst mode laser driver IC. This IC, along with other control circuitry, controls the laser to meet the requirements of the protocol (e.g., depending on whether the network is BPON or GPON).
The downstream video broadcast streams (e.g., 1550 nm) are manipulated by video receiver circuitry which transmits them through the premises via a 75-ohm coaxial cable. Normally, the interface for connecting the PON module to the coaxial cable consists of an interface cable extending from a circuit board within the PON module housing and coupling to a second circuit board at the subscriber location (e.g., within the ONU). This interface cable is expensive and complicates manufacturing and installation (due, e.g., to its bulk and inflexibility). Also, the large, inflexible and heavy interface cable may place excessive strain on the PON circuit board during transport, installation and use. The strain can be focused at the point at which the interface is coupled (e.g., soldered) to the PON circuit board, which may result in failure of the coupling.